Elvis Presley once appalled members of his own entourage when he became aroused as he simulated a bestial act with record label RCA's mascot dog NIPPER.

In a Playboy expose, The King's secret 'pimp' BYRON RAPHAEL confesses he was shocked as he watched his boss cavort with Nipper onstage at a show in Los Angeles in 1957.

Raphael, who was charged with looking after Nipper at the show, recalls Presley did "the unthinkable" during an encore of his hit HOUND DOG.

He says, "Pumped up by either adrenaline or libido, he began to unfasten his pants and slowly pull down his zipper... Elvis reached for Nipper.

"Suddenly Elvis pressed the dog against his crotch... and he rode the pooch back and forth in a masturbatory glide. As the crowd noise grew to a furious roar, Elvis continued to dry-hum poor Nipper."

Presley is then said to have rolled around the floor with the dog.

Raphael adds, "It was one of the most shocking things I'd ever seen. There's no question that Elvis was trying to have sex, because when he finally gave the dog back to me, I could see a huge hard-on through his pants."

The concert caused such an uproar that the Los Angeles vice squad filmed the next night's show, but Elvis toned that performance down.